<?php

// CONFIG: Enable debug mode. This means we'll log requests into 'ipn.log' in the same directory.
// Especially useful if you encounter network errors or other intermittent problems with IPN (validation).
// Set this to 0 once you go live or don't require logging.
define("DEBUG", 1);
// Set to 0 once you're ready to go live
define("USE_SANDBOX", 1);
define("LOG_FILE", Chemins::CONFIGS."ipn.log");

class Paypal{

    public static function checkPayment(){
        // Read POST data
        // reading posted data directly from $_POST causes serialization
        // issues with array data in POST. Reading raw POST data from input stream instead.
        $raw_post_data = file_get_contents('php://input');
        $raw_post_array = explode('&', $raw_post_data);
        $myPost = array();
        foreach ($raw_post_array as $keyval) {
            $keyval = explode ('=', $keyval);
            if (count($keyval) == 2)
                $myPost[$keyval[0]] = urldecode($keyval[1]);
        }
        // read the post from PayPal system and add 'cmd'
        $req = 'cmd=_notify-validate';
        if(function_exists('get_magic_quotes_gpc')) {
            $get_magic_quotes_exists = true;
        }
        foreach ($myPost as $key => $value) {
            if($get_magic_quotes_exists == true && get_magic_quotes_gpc() == 1) {
                $value = urlencode(stripslashes($value));
            } else {
                $value = urlencode($value);
            }
            $req .= "&$key=$value";
        }
        // Post IPN data back to PayPal to validate the IPN data is genuine
        // Without this step anyone can fake IPN data
        if(USE_SANDBOX == true) {
            $paypal_url = "https://www.sandbox.paypal.com/cgi-bin/webscr";
        } else {
            $paypal_url = "https://www.paypal.com/cgi-bin/webscr";
        }
        $ch = curl_init($paypal_url);
        if ($ch == FALSE) {
            return FALSE;
        }
        curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $req);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
        curl_setopt($ch, CURLOPT_FORBID_REUSE, 1);
        if(DEBUG == true) {
            curl_setopt($ch, CURLOPT_HEADER, 1);
            curl_setopt($ch, CURLINFO_HEADER_OUT, 1);
        }
        // CONFIG: Optional proxy configuration
        //curl_setopt($ch, CURLOPT_PROXY, $proxy);
        //curl_setopt($ch, CURLOPT_HTTPPROXYTUNNEL, 1);
        // Set TCP timeout to 30 seconds
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 30);
        curl_setopt($ch, CURLOPT_HTTPHEADER, array('Connection: Close'));
        // CONFIG: Please download 'cacert.pem' from "http://curl.haxx.se/docs/caextract.html" and set the directory path
        // of the certificate as shown below. Ensure the file is readable by the webserver.
        // This is mandatory for some environments.
        //$cert = __DIR__ . "./cacert.pem";
        //curl_setopt($ch, CURLOPT_CAINFO, $cert);
        $res = curl_exec($ch);
        if (curl_errno($ch) != 0) // cURL error
        {
            if(DEBUG == true) {
                error_log(date('[Y-m-d H:i e] '). "Can't connect to PayPal to validate IPN message: " . curl_error($ch) . PHP_EOL, 3, LOG_FILE);
            }
            curl_close($ch);
            exit;
        } else {
            // Log the entire HTTP response if debug is switched on.
            if(DEBUG == true) {
                error_log(date('[Y-m-d H:i e] '). "HTTP request of validation request:". curl_getinfo($ch, CURLINFO_HEADER_OUT) ." for IPN payload: $req" . PHP_EOL, 3, LOG_FILE);
                error_log(date('[Y-m-d H:i e] '). "HTTP response of validation request: $res" . PHP_EOL, 3, LOG_FILE);
            }
            curl_close($ch);
        }
        // Inspect IPN validation result and act accordingly
        // Split response headers and payload, a better way for strcmp
        $tokens = explode("\r\n\r\n", trim($res));
        $res = trim(end($tokens));
        if (strcmp ($res, "VERIFIED") == 0) {
            // check whether the payment_status is Completed
            // check that txn_id has not been previously processed
            // check that receiver_email is your PayPal email
            // check that payment_amount/payment_currency are correct
            // process payment and mark item as paid.
            // assign posted variables to local variables
            //$item_name = $_POST['item_name'];
            //$item_number = $_POST['item_number'];
            //$payment_status = $_POST['payment_status'];
            //$payment_amount = $_POST['mc_gross'];
            //$payment_currency = $_POST['mc_currency'];
            //$txn_id = $_POST['txn_id'];
            //$receiver_email = $_POST['receiver_email'];
            //$payer_email = $_POST['payer_email'];

            if(DEBUG == true) {
                error_log(date('[Y-m-d H:i e] '). "Verified IPN: $req ". PHP_EOL, 3, LOG_FILE);
            }
        } else if (strcmp ($res, "INVALID") == 0) {
            // log for manual investigation
            // Add business logic here which deals with invalid IPN messages
            if(DEBUG == true) {
                error_log(date('[Y-m-d H:i e] '). "Invalid IPN: $req" . PHP_EOL, 3, LOG_FILE);
            }
        }
    }
}